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Author Topic: 1968 performance  (Read 5110 times)

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mr get

  • Message Board Member but not a NFTAC Club Member
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  • Posts: 1
1968 performance
« on: March 22, 2007, 10:06:28 PM »
I was wondering if someone could tell me what the performance of a 1968 firebird 400 Automatic with 2.56 non posi rear gears. The problem is that I feel I'm not getting the power that maybe this car should have.
I cannot even spin one tire on take off when there is three passagers with me. The engine was over hauled about 20,000 miles ago but it run the same as it did when before, after and now. Prohapes this is the way they run with such tall rear gears. If someone has a simular setup as me, Please let me know so that I can compare. Thank You


  • Firebird & Trans Am Club Tech Staff
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Re: 1968 performance
« Reply #1 on: April 06, 2007, 09:00:20 PM »
That’s not normal / with a 400cu. and a 2.56 Rear Gear you should be able to          light’em – up!

Assuming your engine runs fine: good compression, no vacuum leeks etc.
Did you consider checking your Transmission?

a.Check the Transmission fluid {ATF} for proper level and color, the normal color of automatic transmission fluid is a deep red or orange red; and it shouldn’t be Black, Brown, Green/Brown or Pink
b.It shouldn’t have a burned odor to it. (If the color of the ATF is Black or Brown shaded and has a burned odor to it their is a good possibly the Transmission is damaged and servicing of the ATF fluid; and filter at this point may not help

c.Check the Trans./ Modulator to see if defective, an Modulator Vacuum Hose for it’s condition and for proper installation // (check for cracks or broken)

Examining the {ATF} fluid color as follows:

Remove the Trans./ Dipstick wipe the fluid onto a white paper this will allow you to see the true color of the ATF fluid as it adsorbed into the paper.

a.If the ATF fluid is Pink shade and/or milky feel to it; the Transmission fluid cooler in the Radiator is leaking coolant into the Transmission oil cooler lines and it will damage the Transmission (The Ethylene Glycol in the antifreeze breaks down the bonding material in the bands and / or clutch discs.)

b.If the ATF fluid is Red but is foamy – bubbles the fluid level is to high.

c.If the ATF fluid is Green / Water Contamination which can damage the Transmission.

d.If the ATF fluid has large amounts of particles that are found / The Transmission bands, clutches and / or friction material, could be worn or damaged

Also Conduct a Road Test:

While driving try to note any unusual operations in the Transmission such as:


b.Unusual Noise
c.Poor Shifting Quality


e.Erratic Shift Pattern's

f.Note if you can how many Gears being Shifted 1. into 2. ect. In the Transmission

And finally check the Rear End:

With Jack Stands and the rear wheels off the ground check it’s operation etc.

Hope This Can Be Of Some Help To You.  :) 

                                                         Justin K.
« Last Edit: April 07, 2007, 01:55:08 AM by T/A JLK »
I am a NFTAC, Member and I was at one time an auto mechanic working for a local GM dealer here in my home town back in the mid-to late '80's now  I currently enjoy working on my own Pontiac's especially on my '85 T/A // making maintenance repairs, repairs, modifications and performance modifications I also enjoy meeting and /or talking to other Firebird & T/A owners an get into technical debates;hopefully just as long as the debate's doesn't go into a to heated argument.

National Firebird and Trans Am Club Message Board

Re: 1968 performance
« Reply #1 on: April 06, 2007, 09:00:20 PM »


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